Scheduled recall in a hierarchical shared storage system

Abstract

In a hierarchical storage management system (HSM), a scheduled-recall request is associated with a start-time. Prior to the scheduled-recall request start-time, if a first recall request is directed to the same storage medium as is the scheduled-recall request, the method performs some or all of the scheduled-recall request, with low priority processing, during times that the storage drive (performing the first recall request) is otherwise idle. After the scheduled-recall request start-time, the priority of the scheduled-recall request is increased and data targeted by the scheduled-recall request, that had not already been recalled during the low priority processing, are subsequently processed with high priority.

What is claimed is: 
     
       1. A method for processing recall requests in a hierarchical storage management system, the method comprising:
 receiving, via a scheduled recall interface, a plurality of recall requests, including a first recall request, wherein:
 the first recall request is for at least a subset of a plurality of data units to be recalled from a second layer of the hierarchical storage management system to a first layer of the hierarchical storage management system, and 
 the first recall request is associated with a first time-slot; 
 
 assigning a respectively corresponding time-variable recall priority to the first recall request; and 
 copying, in a sequential manner, from the second layer to the first layer, the at least a subset of the plurality of data units respectively corresponding to the plurality of recall requests, based at least in part on the respectively corresponding time-variable recall priority; 
 wherein the scheduled recall interface receives recall requests that include respectively corresponding start times. 
 
     
     
       2. The method of  claim 1 , wherein the time-variable recall priority has a first priority corresponding to any time outside of the first time-slot, and a second priority corresponding to any time within the first time-slot, the second priority representing a higher priority than the first priority. 
     
     
       3. The method of  claim 2 , further comprising:
 assigning the first time-slot to a first user; and 
 assigning a second time-slot to a second user wherein the second user requests recall of the at least a subset of the plurality of data units to be recalled. 
 
     
     
       4. The method of  claim 3 , wherein the first time-slot and the second time-slot are based, at least in part, on a threshold time specified by the second user, the threshold time being indicative of a time after which recall processing is to be started. 
     
     
       5. The method of  claim 4 , wherein the at least the subset of the plurality of data units to be recalled are identified, based at least in part on at least one file path specified by the second user. 
     
     
       6. The method of  claim 5 , further comprising:
 generating a scheduled recall request list containing information indicative of the identified data units and the threshold time. 
 
     
     
       7. The method of  claim 6 , further comprising:
 scheduling a second recall request to which the time-variable recall priority is not assigned. 
 
     
     
       8. The method of  claim 7 , further comprising:
 in response to receiving the second recall request, identifying a first target storage medium on which a first data unit requested by the second recall request is stored; 
 determining a scheduled recall request list contains information indicative of the identified data units and the threshold time; 
 identifying a second target storage medium on which a second data unit requested by a scheduled recall request listed in the scheduled recall request list is stored; 
 determining that the first target storage medium and the second target storage medium are a single common target storage medium; 
 requesting recall processing on the first and second data units stored in the common target storage medium; and 
 while the common target storage medium is mounted in a drive unit, performing recall processing for the second recall request and the scheduled recall request. 
 
     
     
       9. The method of  claim 6 , further comprising:
 in response to the second time-slot being started, performing a recall process for recall requests remaining listed in the scheduled recall request list. 
 
     
     
       10. A computer program product for processing recall requests in a hierarchical storage management system, the computer program product comprising a computer readable storage medium having stored thereon program instructions programmed to perform:
 receiving, via a scheduled recall interface, a plurality of recall requests, including a first recall request, wherein:
 the first recall request is for at least a subset of a plurality of data units to be recalled from a second layer of the hierarchical storage management system to a first layer of the hierarchical storage management system, and 
 the first recall request is associated with a first time-slot; 
 
 assigning a respectively corresponding time-variable recall priority to the first recall request; and 
 copying, in a sequential manner, from the second layer to the first layer, the at least a subset of the plurality of data units respectively corresponding to the plurality of recall requests, based at least in part on the respectively corresponding time-variable recall priority; 
 wherein the scheduled recall interface receives recall requests that include respectively corresponding start times. 
 
     
     
       11. The computer program product of  claim 10 , wherein the time-variable recall priority has a first priority corresponding to any time outside of the first time-slot, and a second priority corresponding to any time within the first time-slot, the second priority representing a higher priority than the first priority. 
     
     
       12. The computer program product of  claim 11 , further comprising program instructions programmed to perform:
 assigning the first time-slot to a first user; and 
 assigning a second time-slot to a second user wherein the second user requests recall of the at least a subset of the plurality of data units to be recalled. 
 
     
     
       13. The computer program product of  claim 12 , wherein the first time-slot and the second time-slot are based, at least in part, on a threshold time specified by the second user, the threshold time being indicative of a time after which recall processing is to be started. 
     
     
       14. The computer program product of  claim 13 , wherein the at least the subset of the plurality of data units to be recalled are identified, based at least in part on at least one file path specified by the second user. 
     
     
       15. The computer program product of  claim 14 , further comprising program instructions programmed to perform:
 generating a scheduled recall request list containing information indicative of the identified data units and the threshold time. 
 
     
     
       16. The computer program product of  claim 15 , further comprising program instructions programmed to perform:
 scheduling a recall request to which the time-variable recall priority is not assigned. 
 
     
     
       17. The computer program product of  claim 16 , further comprising program instructions programmed to perform:
 in response to receiving the recall request, identifying a first target storage medium on which a first data unit requested by the recall request is stored; 
 determining a scheduled recall request list contains information indicative of the identified data units and the threshold time; 
 identifying a second target storage medium on which a second data unit requested by a scheduled recall request listed in the scheduled recall request list is stored; 
 determining that the first target storage medium and the second target storage medium are a single common target storage medium; 
 requesting recall processing on the first and second data units stored in the common target storage medium; and 
 while the common target storage medium is mounted in a drive unit, performing recall processing for the recall request and the scheduled recall request. 
 
     
     
       18. The computer program product of  claim 15 , further comprising program instructions programmed to perform:
 in response to the second time-slot being started, performing a recall process for recall requests remaining listed in the scheduled recall request list. 
 
     
     
       19. A computer system for processing recall requests in a hierarchical storage management system, the computer system comprising:
 a processor set; and 
 a computer readable storage medium; 
 wherein:
 the processor set is structured, located, connected and/or programmed to run program instructions stored on the computer readable storage medium; and 
 the program instructions include program instructions programmed to perform:
 receiving, via a scheduled recall interface, a plurality of recall requests, including a first recall request, wherein;
 the first recall request is for at least a subset of a plurality of data units to be recalled from a second layer of the hierarchical storage management system to a first layer of the hierarchical storage management system, and 
 the first recall request is associated with a first time-sot; 
 
 assigning a respectively corresponding time-variable recall priority to the first recall request; and 
 copying, in a sequential manner, from the second layer to the first layer, the at least a subset of the plurality of data units respectively corresponding to the plurality of recall requests, based at least in part on the respectively corresponding time-variable recall priority; 
 wherein the scheduled recall interface receives recall requests that include respectively corresponding start times. 
 
 
 
     
     
       20. The computer system of  claim 19 , wherein the time-variable recall priority has a first priority corresponding to any time outside of the first time-slot, and a second priority corresponding to any time within the first time-slot, the second priority representing a higher priority than the first priority.